"It misses the fact that there are now very few reasons..."
I'm going to take the wild guess you're male. As an old married guy with a daughter I can assure you there is enormous investment in advertising money to specifically get females interested in spending around the cost of a cheap new car to get married.
I'm not even claiming this is a large part of the reason for marriage propaganda, however, thousands of advertising dollars are spent to convince females that spending tens of thousands on a wedding would be a great idea. Probably fairly heteronormative and once civilization arrives and gay marriage is more widely "permitted" then we'll start to see a lot more advertising dollars spent convincing guys that spending $10K on a wedding is fabulous.
And if you think marriage is expensive, try divorce.
My wife and I paid about $10K for our wedding, and felt we cheap skated out on a few things. This kind of social pressure is fine when its only about one months income, but for poor people, its kind of a dumb social policy. Giving the same $10K to the educational-industrial complex or real estate/banking industries isn't going to improve their lot in life either, so its puzzling.
One interesting thing to think about is our marriage was basically a little ceremony followed by two co-located family reunions, and it cost about $10K. In comparison a couple years ago my wife hosted and organized a family reunion at a city park for her family, about as many people attended, and our out of pocket was $82 for a park pavilion rental. So we're looking at almost two orders of magnitude of cost inefficiency.
There is a large market full of money to solve the difficult problem of providing a storybook princess wedding to women for something between $10K and $100. This is not exactly a stereotypical YC startup idea, but SOMEONE is eventually going to do it and rake in the cash.
Having been a starving student and starting out on a low salary in a medium cost of living area, I assure you there are very few investments available. If I have $10M there are plenty of interesting ways to invest it to improve my life, but if I have $100 laying around there's almost nothing to do with it that is not brainless consumerism or basically throwing it away. You can't bootstrap yourself if you can't invest in any way. Maybe microlending will help, although seems like lots of scams in the field. You'd think advanced computerization and networking would force microinvestment and microtransactions into the financial markets, but you'd be totally wrong. Check the price of NYSE:BRK.A and get back to me. We keep people poor by preventing them from having a profitable use for small amounts of excess money. There's probably a startup idea in there somewhere... a bitcoin powered stock exchange where you can trade any rational fraction of a stock or something like that.